The purpose of the research is to study structure and function of different classes and subclasses of immunoglobulins. Particular emphasis will be placed on the structure of IgD and on the ability of IgE to bind to lymphocytes. In addition, a myeloma IgG half-molecule and a presently not elucidated antigenically and structurally abnormal IgA myeloma protein are investigated. The proposal consists of four projects: 1) the study of the binding of IgE myeloma proteins, both human and rat IgE, to T, B and K lymphocytes; 2) the biological functions of an IgG myeloma protein such as turnover, complement and cell fixation will be analyzed; 3) the amino sequence of the Fc fragment of IgD is being investigated, and; 4) antigen to human IgG subclasses will be prepared in goats made immunologically unresponsive to one IgG subclass.